This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Transcriptome profiling and proteomics are being used to discover the range of acclimation and adaptations to UV-B in maize. Two-dimensional separation (by isoelectric point and by size) is used to fractionate the major proteins of treated and control tissues, providing data on ~3000 resolved protein types. The proteins are classified as unchanged, increased or decreased by specific treatments, and the proteins showing consistent alterations are recovered for identification. All of the protein identification is conducted in collaboration with the UCSF Mass Spectrometry Facility;to date, about 350 proteins have been identified by mass fingerprinting and sequencing. Among these proteins are a number predicted from the transcriptome profiling as well as proteins not previously implicated in responses to either UV-B or transposon-induced genomic damage. The combination of transcriptome profiling and proteomics data are used to determine which signal transduction pathways and cellular processes are involved;verification experiments include genetic analysis of mutants in key processes identified, i.e. by demonstrating that mutants show increased UV-B sensitivity. Current work focuses on elucidating post-translational modifications of proteins that were not altered in abundance by the treatments, followed by identification by mass spectrometry. These studies will likely highlight the most rapid responses to the treatments.